Trump knew Flynn misled WH weeks before ouster: officials

White House National Security Advisor Michael Flynn (C) arrives prior to a joint news conference between Canadian Prime Minister Justin Trudeau and US President Donald Trump at the White House in Washington, US, February 13, 2017. [Photo/Agencies]

At the same time, the official said Trump aides began taking steps to put some distance between the president and Flynn. CIA Director Mike Pompeo and retired Lt. Gen. Keith Kellogg, a top Flynn aide, started taking part in Trump's daily security briefings.

Top Trump advisers quietly met with Vice Admiral Robert Harward last week and spoke with the former Navy SEAL again Monday, the White House official said. Harward is seen as the top contender for the job, though former CIA Director David Petraeus and Kellogg, who has temporarily stepped into the role, are also under consideration.

Spicer said other "questionable incidents" had contributed to Flynn's firing. According to one person with knowledge of the matter, those incidents included Flynn seeking a security clearance for his son during the transition.

At the time, it was Pence who was again put in the position of defending Flynn on television, saying he had not sought a clearance for the retired general's son.

A US official told The Associated Press that Flynn was in frequent contact with Kislyak on the day the Obama administration slapped sanctions on Russia for election-related hacking, as well as at other times during the transition. Spicer said Flynn was not discussing sanctions at the president's behest.

Before he resigned Monday night, Flynn told the investigative news nonprofit affiliated with the website The Daily Caller that he and Kislyak spoke only generally about the Russian diplomats expelled by President Barack Obama as part of the previous administration's response to Moscow's interference in the US presidential election.

"It wasn't about sanctions. It was about the 35 guys who were thrown out," Flynn said. "It was basically: 'Look, I know this happened. We'll review everything.' I never said anything such as, 'We're going to review sanctions,' or anything like that."Associated Press writers Jonathan Lemire, Eric Tucker, Ken Thomas, Jill Colvin, Erica Werner and Catherine Lucey contributed to this report.